Recording tapes using iron nitride fine powder

Magnetic recording pigment of Fe4N particles was prepared by nitrogenizing acicular metal iron powder. The treatment to obtain stoichiometric Fe4N was carried out at 400°C for 3 hours in NH3-H2(3:1) mixed gas. The saturation magnetization and coercive force were 120 emu/g and 700 Oe respectively. The Curie point of the powder coincided well with that of bulk material. Test tapes were prepared with this Fe4N powder. The remanent magnetic flux density (Br) of the tape was 2200 G and the coercive force was 670 Oe. From test immersion in saline solution, it is confirmed that the chemical stability of the Fe4N tape is superior to the Fe4N tape is superior to the metal tape.